34 lines
1.0 KiB
Rust
34 lines
1.0 KiB
Rust
|
pub fn plus_one(digits: Vec<i32>) -> Vec<i32> {
|
||
|
|
// Keep track of when to carry for the next digit.
|
||
|
|
let mut carry = false;
|
||
|
|
|
||
|
|
// Reverse the digits so they're from least to most significant.
|
||
|
|
let mut digits = digits.into_iter().rev();
|
||
|
|
|
||
|
|
// Create a vector to store the incremented digits.
|
||
|
|
let mut incremented = vec![];
|
||
|
|
|
||
|
|
while let Some(digit) = digits.next() {
|
||
|
|
if digit == 9 {
|
||
|
|
// When the current digit is 9 save 0 and keep going through the digits.
|
||
|
|
incremented.push(0);
|
||
|
|
carry = true;
|
||
|
|
} else {
|
||
|
|
// When the digit isn't 9, increment it and save it, set carry to false
|
||
|
|
// and break the loop early.
|
||
|
|
incremented.push(digit + 1);
|
||
|
|
carry = false;
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// If the last digit was a 9 we have to add an extra 1, for example:
|
||
|
|
// [9] turns into [0] and then here we make it [0, 1].
|
||
|
|
if carry {
|
||
|
|
incremented.push(1);
|
||
|
|
}
|
||
|
|
|
||
|
|
// Then reverse both iterators so they're in the correct order and chain them.
|
||
|
|
digits.rev().chain(incremented.into_iter().rev()).collect()
|
||
|
|
}
|